Mission to Jupiter: 25 Years Since the Launch of Galileo (Part 2)

By Ben Evans, on October 12th, 2014

Atlantis roars into orbit on 18 October 1989 to deploy the Galileo spacecraft on its mission to Jupiter. Photo Credit: NASA

Twenty-five years ago, next week, shuttle mission STS-34 and the crew of Atlantis rocketed into orbit to launch NASA’s Galileo spacecraft on a lengthy odyssey to Jupiter. As described in yesterday’s AmericaSpace history article, the mission was extensively delayed, by political and technical issues—including the Challenger tragedy—and almost met with outright cancellation, when anti-nuclear protesters campaigned against the use of its plutonium-powered Radioisotope Thermoelectric Generator (RTG). However, after considerable rain, on the wet morning of 18 October 1989, the five astronauts departed their crew quarters at the Kennedy Space Center (KSC), bound for Pad 39B and Atlantis.

In command of STS-34 was Don Williams, who had previously flown as pilot of Mission 51D in the spring of 1985. He was joined by pilot Mike McCulley and mission specialists Shannon Lucid—a veteran of the multi-national Mission 51G—Franklin Chang-Díaz, and Ellen Baker. The quintet had been training since November 1988. Their launch on 18 October was postponed by 3.5 minutes, in order to update the shuttle’s computers for a change in the Transoceanic Abort Landing (TAL) site, which had been moved to Zaragoza in Spain, due to heavy rain at Ben Guerir in Morocco. Finally, at 12:53 p.m. EST, Atlantis thundered into clear Florida skies, bound for low-Earth orbit.

Despite all of his training, the dynamic nature of the launch surprised Mike McCulley, who described much of its effect as “acoustic,” which “shakes your body and your soul.” At one stage, a few seconds after liftoff, as the tower disappeared faster than his simulator experience had taught him to expect, he turned to Williams and jokingly remarked: “You didn’t prepare me for this!” Another thing which came as unexpected was the separation of the twin Solid Rocket Boosters (SRBs), about two minutes into the ascent. “In the simulator, there’s a flashbulb that goes off when you get to SRB sep,” McCulley told the STS-34 post-flight press conference, “and in real life there’s an explosion that goes off, right in front of your face. It was wonderful … but it was surprising!”

Emblazoned with the script-like “Galileo” lettering and the block “NASA” letters, the spacecraft represented a marriage of romance and adventure with science and technology for STS-34’s Shannon Lucid. Photo Credit: NASA

To be fair to Williams, his position in command of STS-34 was quite distinct to his previous stint as a shuttle pilot. “There’s some amount of loneliness at the top,” he told the NASA oral historian, “and having that authority and with it comes the responsibility for accomplishing the mission. With those first two comes the most important one, in my mind, which I learned early on as a midshipman at Purdue … is with the authority and responsibility comes the accountability and if something goes wrong, it’s not somebody else’s fault, it’s the person in command’s fault! The same thing is true when you command a mission. You’re accountable for the performance of the crew, for the accomplishment of the mission, for getting the objectives completed successfully, and for getting the spacecraft back so somebody else can use it again. That’s the name of the game.” Command was important to Williams. In fact, by his own admission, it was his primary goal as a pilot: to command the shuttle. “Okay, this is what you came here for,” he told himself. “Let’s go do it.”

Six hours into the mission, at 7:15 p.m., under the watchful eye of Shannon Lucid, Galileo and its Boeing-built Inertial Upper Stage (IUS) booster were tilted to their deployment position and set free. “Galileo is on its way to another world,” exulted Williams. “It’s in the hands of the best flight controllers in the world. Fly safely!” Franklin Chang-Díaz felt a very personal affinity with Galileo. To him, it was a memorable occasion, because it represented his childhood desire to leave Earth and travel to other planets. Shortly thereafter, Williams and McCulley maneuvered Atlantis to a safe separation distance, and the IUS fired to boost Galileo onto a course for Venus, which it would reach in a little over three months’ time.

“Both Ellen and I sighed a great sigh of relief,” recalled Lucid, “because we figured Galileo was not our concern at that point, because we’d gotten rid of it. Happiness was an empty payload bay and we got happier and happier as the IUS and Galileo went further away from us.” An hour after deployment, the IUS fired to commence Galileo’s six-year journey to the King of the Planets.

As circumstances transpired, it would prove a remarkable example of the triumph of human ingenuity over adversity. Eighteen months into its cruise, and several months after its first flyby of Earth, Galileo’s high-gain antenna only partially unfurled, threatening to ruin the mission. “Workaround” techniques were devised to use the low-gain antenna instead, and the spacecraft returned remarkable images from the asteroids Gaspra (in October 1991) and Ida (in August 1993) and, far from conducting two years of scientific exploration at Jupiter, Galileo spent almost eight years in operation. During that period, it measured the chemical composition of the giant planet’s atmosphere, directly observed its ammonia clouds and mysterious Great Red Spot, analyzed the causes and effects of volcanism on Io, and yielded tantalizing clues for liquid oceans beneath the frozen surfaces of Europa and Ganymede, and the extent of Jupiter’s gigantic magnetosphere was mapped and modeled for the first time. On its way to the planet, in July 1994, Galileo also observed the impact of Comet Shoemaker-Levy 9 into the Jovian clouds.

Having set Galileo on its way, for all intents and purposes, the primary mission of STS-34 was over. Several secondary experiments were performed, including the first flight of the Shuttle Solar Backscatter Ultraviolet (SSBUV) instrument in the payload bay. This was part of an ongoing NASA effort to calibrate ozone sounders on free-flying satellites and verify the accuracy of atmospheric ozone and solar irradiance data. A polymer solidification study was conducted on the middeck, and observations were made of lightning events in the high atmosphere.

Living in space, even for just five days, was quite different to anything the astronauts had experienced before. Williams described it as akin to a camping trip, with the exception that none of them departed their camper van, at all, for the entire five days. “What’s it like to be in space?” he rhetorically asked his audience at the STS-34 post-flight press conference. “Unfortunately, this is one of the most difficult questions to answer, since the word ‘like’ implies a comparison, and it’s not ‘like’ anything you’ve ever done before. So most of us are stuck with describing the differences. Weightlessness. How do you describe weightlessness, when we live in a world where everything weighs something? The ability to move about, almost be thinking about it. No up or down. Behavior and misbehavior of common, ordinary things, such as liquids, elastic, food, objects.

“Watch the video with us,” Williams invited his audience. “Compare it to things you do on Earth. Look for the differences. Perhaps you can describe ’em to us!”

Betwixt this wonderland of weightlessness, the crew was periodically called away to tend to minor issues with Atlantis herself. A problem with one of the shuttle’s Auxiliary Power Units (APUs) triggered an alarm on 22 October, together with a glitch with the Flash Evaporator System (FES) and cryogenic oxygen manifolds. Predicted high winds at Edwards Air Force Base, Calif., on the 23rd prompted a decision to bring the shuttle home two orbits earlier than planned, and Williams and McCulley guided the shuttle to a smooth touchdown at 6:33 a.m. PST (12:33 p.m. EST), just 20 minutes short of five full days after launch.

Don Williams regarded STS-34 and having accomplished something quite remarkable for science. “We knew that Galileo was going to be a lasting program,” he said, “as opposed to the first flight, where we deployed the two satellites. The Galileo mission, we knew, if it was successful, the spacecraft was going to end up in orbit around Jupiter several years later and then there were going to be several years of data and images sent back. It was going to be a living, ongoing program and we got to be a part of it.”

This is part of a series of history articles, which will appear each weekend, barring any major news stories. Next week’s article will focus on STS-58, a controversial shuttle mission from October 1993, which featured the first euthanasia and dissection of living animals in microgravity.

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